Reigning King of DIY headphone amps?
Jun 5, 2007 at 5:42 PM Post #16 of 53
hi mr. gilmore, what is your thought about the measurements between the Dynahi and the Beta22? I've always been interested in comparing these two amps. What do you think is causing the ringing at 100kHz square wave on the Dynahi? I will try changing some of the values of the capacitors to see if it fixes things, since I think that may be the cause.

dynahi_100khz_sq3.jpg


I will try the S22 power supply with the Dynahi and see what happens. With the Dynahi power supply, there is clipping at higher volumes on my speaker.
 
Jun 5, 2007 at 7:38 PM Post #19 of 53
Quote:

Originally Posted by colonelkernel8 /img/forum/go_quote.gif
Lets not start, ok? Wow.


are you refering to me? not trying to "start" anything at all, just discussing the design differences between the two big DIY amps. i'm highly interested in amp design, and am learning/studying the effects of measurements on subjective sound.

Quote:

Originally Posted by balou
anybody got an idea what the king of the all-ic amps would be? is it the ppa v1?


I think the Jan Meier stuff, based on looking at the design.
 
Jun 5, 2007 at 8:00 PM Post #20 of 53
Quote:

Originally Posted by cotdt /img/forum/go_quote.gif
I think the Jan Meier stuff, based on looking at the design.


I would think the M³, since it measures better than both the β22 and the dynahi, but is clearly less powerful.
 
Jun 5, 2007 at 8:06 PM Post #22 of 53
Quote:

Originally Posted by n_maher /img/forum/go_quote.gif
I would think the M³, since it measures better than both the β22 and the dynahi, but is clearly less powerful.


yes, but balou asked for "all-IC" amps
 
Jun 5, 2007 at 8:18 PM Post #23 of 53
yes, I'm interested in all-ic designs to 'borrow' some ideas for my next amp
biggrin.gif

I found the porta corda design here, but I don't think it really is a top class design (well, it is a portable design, so it's main design goal should be ...portability). Are there any other Jan Meier circuits available?
 
Jun 5, 2007 at 10:14 PM Post #25 of 53
The ringing square wave is on a dynahi built with a gain of 7. At the "stock" gain of 13 it probably won't ring (and the square wave behavior changes depending on the amplitude). The amp must be compensated differently because it would be operating at a different point on the gain-bandwidth graph (wider bandwidth as closed loop gain is lowered), and there will be less phase margin.

The stock gain is too high for most headphones, though.
 
Jun 5, 2007 at 10:21 PM Post #26 of 53
Quote:

Originally Posted by kevin gilmore /img/forum/go_quote.gif
I'm pretty sure this picture is 100khz, there were others i think
can't find them at the moment.
http://gilmore.chem.northwestern.edu/dynarise.jpg


I definitely recall seeing other 'scope measurements of the Dynahi. There was a clear picture of a Dynahi putting out textbook perfect 100kHz square waves into a 33 Ohm load, and as I remember it you actually burnt out the load resistor which was at least a 5W unit. Fun times!
 
Jun 5, 2007 at 11:57 PM Post #27 of 53
I have enough trouble remembering what i did last week let alone
3.5 years ago. Anyway at a gain of 5 i remember all you really had
to do was put in a 100 ohm series resistor on the input to the amp.
Similar to an LH0033 i think. Dynafet has the 100 ohm resistor.
 
Jun 6, 2007 at 12:05 AM Post #28 of 53
Got a link for the dyna-gbf-fet schematics? I'm not familiar with DIY, but I've been thinking about having my EE engineer friend build me a balanced b22 or perhaps a dyna-gbf-fet. Are there boards/what have you for this?
 
Jun 6, 2007 at 12:42 AM Post #29 of 53
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